If you buy a Windows 8-powered HP consumer PC, or from any other PC vendor, you'll get no help from them if you decide you'd rather have Windows 7. And Linux? Forget about it!
Well if you are planning on running Linux, you are going to have to get use to doing things on your own. You can certainly install Windows 7 , but you will need to have a licensed copy. If you want it pre installed you can probably order a PC from any vender with a request for Windows 7. Are you having issues with 8?